CODEWITHSUNDEEP
rdataframesubset
RNewbie
RNewbie

Reputation: 37

Subset dataframe by row values of another dataframe

i am trying to subset a dataframe with extracted data from another dataframe. My data looks essentially like this:

PriceData

Date          AAPL   BAC   CAT    JNJ    PG    UNH   VZ
2004-04-26     
2004-04-27            Daily Prices
2004-04-28     
2004-04-29     


Companies

Date          X1     X2     X3    X4
2004-04-26   AAPL   CAT     PG    VZ
2004-04-27   AAPL   CAT     UNH   VZ
2004-04-28   AAPL   JNJ     UNH   VZ
2004-04-29   AAPL   JNJ     UNH   VZ

I have already managed to subset the Companies dataframe by date, so i have a dataframe with one row containing the tickers of a specific date. For instance:

Tickers
Date          X1     X2    X3    X4
2004-04-28    AAPL   JNJ   UNH   VZ

What i would like to do now is to subset the PriceData dataframe so that only the price data of the four tickers in Tickers remain:

newPriceData

Date          AAPL    JNJ    UNH    VZ
2004-04-26
2004-04-27        Daily Prices
2004-04-28
2004-04-29

Does anybody know what package/function i could use to achieve this?

Upvotes: 0

Views: 61

Answers (1)

smingerson
smingerson

Reputation: 1438

Base R, data.table, and dplyr solutions. data.table and dplyr are packages which provide alternative functions for data manipulation. I encourage you to look into both -- each is much more flexible and convenient than base R subsetting. You can find the CRAN pages here and here. They each have a vignette (tutorial) listed as "Introduction to ".

Below I've listed a corresponding command for each. For dplyr and data.table, there are slight variations of those listed which might be considered more natural for dplyr or data.table, but these contain the smallest diversions from a similarity to base syntax.

columns_to_retain <- unlist(Tickers[1,-1]) # Take the first row, drop the first column, convert to plain vector.
NewPriceData <- PriceData[,columns_to_retain]

# dplyr
library(dplyr)
NewPriceData <- select(PriceData, columns_to_retain) # or names(Tickers) instead of columns_to_retain

# data.table
NewPriceData <- PriceData[,columns_to_retain, with = FALSE]

Upvotes: 1

Related Questions